Fig. 4

Students' knowledge about five key principles of evolution by natural selection was measured with the CINS and the Dino Problem before and after instruction on evolution (n = 124). The maximum possible score on each instrument was ten points. a The mean score for both instruments improved after instruction. Application of the Wilcoxon matched-pairs signed-rank test indicated that the changes were statistically significant with α < 0.005. b A visual representation of the data, indicating the pretest–post-test score distribution among individual students. The gray-shaded squares at the intersection of pretest and post-test scores represent the number of students who received a given combination of scores. Diagonals indicate no change between pretest and post-test; individuals below the diagonal performed better in the pretest than in the post-test. The majority of individuals improved their scores in the post-test and are, therefore, represented above the diagonal